Exhaust emissions from internal combustion engines are significant contributors to pollution in the environment. In particular, nitrogen oxide and nitrogen dioxide (collectively, NOx) emissions contribute to smog and acid rain. NOx is a byproduct of the combustion of fossil fuels, and diesel engines are regarded as a major generator of NOx.
A natural gas fuel can provide improved emissions quality when compared to conventional fuels in combustion engine applications. Natural gas is available in the form of compressed natural gas (CNG) or liquid natural gas (LNG). However, the present use of natural gas in combustion engines is limited generally to CNG, which has certain disadvantages, such as carrying a risk for causing explosions. LNG, on the other hand, and cryogenic fuels more generally, requires careful handling and specialized components to prevent freezing due to the low temperatures at which the fuel is maintained.
Consequently, there is a continuing need for an improved combustion engine and a method to fuel the combustion engine with cryogenic fuels.